* added utf-8 markers to all .py files in plugins/{action,cache,callback}
* added utf-8 markers to all .py files in plugins/connection
* added utf-8 markers to all .py files in plugins/doc_fragments
(cherry picked from commit 73c27d6a0e)
Co-authored-by: Alexei Znamensky <103110+russoz@users.noreply.github.com>